2006-09-15 04:58:00 · 3 answers · asked by lyn_zie2003 1 in Education & Reference ➔ Other - Education
-4+2root3 and -4-2root3
2006-09-15 05:03:06 · answer #1 · answered by cool_zone 2 · 0⤊ 0⤋
you need to add something to both sides so that the left side can be expressed as (x+b)^2 . That multiplies out to
x^2 + 2bx + b^2. Comparing that to the original, we see that
2b = 8 so b=4 and b^2 =16. So you have to add 12 to both sides of the original, giving you x^2 + 8x + 16 = 12. Now the left side
factors nicely into (x+4)^2 = 12 so x + 4 = sqrt(12). You can take it from there.
2006-09-15 12:14:24 · answer #2 · answered by banjuja58 4 · 0⤊ 0⤋
there's a formula which is very useful to solve any quadratic expression
X = (-b + sqrt(D)) / 2a or X = (-b - sqrt(D)) / 2a
D= b^2 - 4(a) (c)
The indices a,b, and c is as the following
ax^2 + bx + c = 0
Thus, from the equation,
a = 1
b = 8
c = 4
as such,
D = 8^2 - 4 (1) (4)
D = 64 - 16 = 48
Thus,
x = (-8 + sqrt(48))/ 2 (1) or X = (-8 - sqrt(48))/ 2 (1)
x = (-8 + 6.93) / 2 or x = (-8 -6.93) / 2
x = -0.54 or x = -7.47
Hope it helps
2006-09-15 13:10:02 · answer #3 · answered by edsis_sg 2 · 0⤊ 0⤋